Shuaiyu Jiang

Lumpy skin disease (LSD) is a transboundary viral disease of cattle for which rapid antigen detection could support field surveillance and outbreak investigations. This study aimed to develop and preliminarily evaluate a colloidal gold immunochromatographic strip targeting the P32 protein of lumpy skin disease virus (LSDV). Recombinant P32 proteins were expressed in Escherichia coli, and two P32-specific monoclonal antibodies, 5B1 and 7H4, were generated using hybridoma technology. Indirect ELISA with truncated P32 fragments showed that both antibodies reacted predominantly with P32-1 (amino acids 13–60), although their precise epitopes were not determined. Of four antibody combinations tested, gold-conjugated 5B1 paired with immobilized 7H4 produced the strongest test-line signal and was selected for strip development. Using recombinant His-tagged P32, the lowest concentration consistently detected in three replicate tests was 40 μg/mL, with results read after 15 min. The strip reacted with LSDV suspension and LSDV-positive skin nodule tissue, while no positive reactions were observed with the selected heterologous viral preparations or negative controls. In an evaluation of 30 bovine clinical specimens, the strip detected 9 of 11 qPCR-positive samples and correctly classified all 19 qPCR-negative samples. Using qPCR as the comparator method, positive percent agreement was 81.82% (95% CI, 48.22–97.72%), negative percent agreement was 100% (95% CI, 82.35–100%), and overall agreement was 93.33%. These findings demonstrate the feasibility of a P32-based antigen detection strip, although its diagnostic performance requires further evaluation in larger and more representative sample sets.

During 2022–2024, a highly pathogenic avian influenza virus (HPAIV) H5N1 strain, designated A/Seagull/Hebei/qhd6/2024 (H5N1), was isolated from migratory birds in Beidaihe National Wetland Park, North China. Phylogenetic analyses revealed that its hemagglutinin (HA) gene belongs to the 2.3.4.4b clade, while the neuraminidase (NA) gene and internal genes clustered with strains originating from multiple continents, consistent with a transcontinental reassortment event. The virus also exhibited 90.1–98.1% nucleotide homology with human-derived H5N1 isolates. Molecular characterization identified key virulence-associated mutations, including the classic HPAIV HA cleavage site, HA-T160A (associated with enhanced human receptor-binding capacity), and NA-I117T (potentially linked to drug resistance). BALB/c mouse infection experiments confirmed systemic replication and high pathogenicity of strain qhd6, with a 50% lethal dose (LD50) of 0.95 log₁₀EID₅₀/mL. Antigenic analysis revealed good cross-reactivity with the widely used H5-Re14 vaccine strain. This study reports the identification, in Beidaihe National Wetland Park, of an HPAIV H5N1 strain whose genetic characteristics suggest intercontinental reassortment and indicate cross-species transmission risk. It clarifies the genetic characteristics and pathogenicity of this strain, providing an important theoretical and practical basis for precise surveillance, risk early warning, and comprehensive prevention and control of AIV at migratory bird stopover sites in North China.

Swine influenza virus (SIV) continues to evolve and possesses notable zoonotic potential, making it an important respiratory pathogen of concern for both the global swine industry and public health. Owing to antigenic drift, genetic reassortment, and regional lineage diversity, vaccine efficacy against SIV shows marked variability across different epidemiological contexts. Therefore, establishing appropriate animal models to dissect its pathogenic mechanisms, transmission characteristics, and immune response patterns is of critical importance. This review systematically summarises the animal models commonly used in SIV research, including mice, ferrets, guinea pigs, pigs, and non-human primates, and provides an integrated analysis across three core dimensions: pathological manifestations, viral replication kinetics, and immune architecture. The evidence indicates that substantial inter-model differences exist in pulmonary lesion distribution, transmission efficiency, mucosal immune development, and cellular immune complexity, which in turn define their functional roles in mechanistic studies, transmission research, and vaccine evaluation. Building on this framework, this review further emphasises the value of a tiered, multi-model strategy in SIV research. In vitro systems and mouse models are well suited for early mechanistic exploration and preliminary vaccine screening; ferret and guinea pig models facilitate the evaluation of transmission dynamics; and the pig model, as the natural host system, remains the critical platform for confirming protective efficacy, identifying potential immunopathological risks, and assessing translational relevance. Importantly, the potential occurrence of vaccine-associated enhanced respiratory disease under antigen-mismatched conditions highlights the need to evaluate both protective performance and immunological safety during vaccine development. Overall, rational integration of evidence across multiple models, anchored to the natural host, will improve the predictability and translational reliability of SIV vaccine research.